Climate change and seismic resilience: Key considerations for Alaska’s infrastructure and built environment

We think at great length, in terms of strong ground motion during earthquakes. There’s a lot of [building] code that is devoted to making sure that structures can withstand strong shaking. That’s all worthless if the ground beneath the building moves, doesn’t matter. It doesn’t matter how you build it if the underlying soils are compromised. Building foundation technologies as potential solutions Interview and workshop participants discussed several solutions and adaptation strategies to reduce the hazard of permafrost degradation on the seismic response of infrastructure systems. Generally, engineers seek to build infrastructure on ice-poor and ice-free terrain, where the amount of soil strength deterioration during thaw is minimal. For infrastructure systems already built on, or placed in, ice-rich permafrost, however, careful monitoring and evaluation of thaw-induced settlement and liquefaction potential of the foundation soil over the design life of the system can reduce risk. When building new infrastructure systems on ice-rich per- mafrost, foundation designs can compensate for permafrost thaw or actively/passively cool the underlying soil layers [69]. Active cooling relies on the use of systems with external power sources to maintain a certain permafrost temperature whereas passive approaches do not rely on external power. Examples of passive systems can be seen in Fig 6 and include elevating a structure off the ground and using passive thermosyphons that employ a working fluid to convect thermal

energy between the ground and atmosphere. Since the 1960s, thermosyphons have been used to stabilize foundations placed in continuous and discontinuous permafrost regions [70]. Thermosyphons have been incorporated into infrastructure design in more than 900 instances in Alaska [69], including about 120,000 thermosyphons installed along the Trans-Alaska Fig 6. Engineering solutions to prevent permafrost thaw below a building [69]. This building features a crawl space between the building and foundation as well as several passive thermosyphons installed throughout the pile foundation system (commonly referred to as thermopiles). https://doi.org/10.1371/journal.pone.0292320.g006 PLOS ONE Climate change and seismic resilience: Key considerations for Alaska’s infrastructure and built environment PLOS ONE | https://doi.org/10.1371/journal.pone.0292320 October 18, 2023 9 / 17